The present invention relates to a pouring device for a steel or molten metal container. More particularly, the present invention relates to a sliding gate valve assembly having a sliding plate and lid in which the sliding plate slides between an open and a closed position to control the flow of molten metal and in which the lid may be locked and hence prevented from moving in a direction parallel to movement of the sliding plate while remaining free to expand in a direction perpendicular to movement of the sliding plate.
Typical sliding gate valve assemblies include a moveable sliding plate sandwiched between two fixed plates. The three plates each contain an aperture or flow opening which are coaxially aligned when the assembly is in an open state. The fixed plates are generally immobilized by a lid or a screw mechanism and the entire assembly is mounted to the underside, coaxially with a pouring opening, of a molten metal container. The sliding plate may then be used to open and close flow from the vessel through the valve assembly.
In U.S. Pat. No. 5,170,915 to Szadkowski, a sliding gate valve is disclosed which has a sliding plate sandwiched between a fixed upper plate and a fixed lower plate. A ring or a lid is used to press or lock the plates together. The lid is stabilized against movement in a direction parallel to movement of the sliding plate by a screw which acts as a locking or clamping device. A disadvantage of this device is that the locking screw tends to come loose as a result of the opening and closing movement of the sliding plate. Additionally, the lid of the Szadkowski device is fixed against vertical movement and thus is unable to compensate for thermal expansion occurring perpendicular to the direction of the movement of the sliding plate.
Hence, a need in the art exists for a sliding gate valve having a lid which may be reliably fixed against movement in a direction parallel to the movement of a sliding plate while remaining free to expand in a direction perpendicular to the movement of the sliding plate in order to compensate for thermal expansion.